Hoist



June 1, 1954 K. HERKER 2,680,004

I HOIST Filed Nov. 24, 1950 2 She-cs-Sheet 1 lnven for- Hera a r June 1,1954 HOIST Filed NOV. 24, 1950 2 Sheets-Sheet 2 fig- 3 /22 ll? I23L/ff/rzg Spee E/eva fion I In venfor K rt/femur K. HERKER I 2,680,004 VPatented June 1, 1954 UNITED STATES ATENT OFFICE Claims priority,application Germany December 3, 1949 2 Claims.

The present invention relates to a hoist, more particularly to a hoistsuch as used in workshops and the like for lifting or loweringcomparatively small loads at different speeds. Prior to the presentinvention hoists of this type were either equipped with a variable speedmotor or with a main lifting motor and a supplemental load adjustingmotor, the latter being adapted to be optionally connected with thelifting drum in lieu of the main lifting motor. In a prior hoist of thatkind the load adjusting motor was equipped with an axially shiftablearmature adapted by its shifting motion to be connected with the liftingdrum. The speed of operation of the main lifting motor was capable ofreduction by the insertion of electrical resistances. Hoists of thatkind were complicated and expensive.

It is the main object of the present invention to provide a hoist whichis capable of lifting and lowering the load at diiferent speeds, but ismuch simpler in design and more reliable in operation and less expensiveto manufacture than the prior variable speed hoists.

It is a further object of the present invention to reduce the powerrequired for operation of the hoist, thus enabling a smaller electricalmotor to be used than was possible in prior designs.

Further objects of the present invention will appear from thedescription of two preferred embodiments thereof which are illustratedin the accompanying drawings, whereas the features of novelty will bepointed out in the claims.

Fig. 1 is an elevation of the novel hoist;

Fig. 2 is the section taken along line 22 of Fig. 1;

Fig. 3 illustrates a plan view of a motor-driven hoist, partly shown insection;

Fig. 4 is a chart diagrammatically illustrating the lifting speed of theload in dependence on the elevation thereof.

The supporting structure of the hoist shown in Figs. 1 and 2 is formedby a casing l integral with upper transverse beam l2 having lugs II forattachment thereof to the ceiling of a workshop or to a suitablecarriage running on rails beneath such ceiling. The casing [0 hassuitable bearings I 3 in which the shaft of a worm M is J'ournalled.This shaft is connected with the motor shaft of an electric motor I5suitably attached to the casing l0. Beneath the worm I4 and extending ata distance therefrom transversely thereto, there is journalled a shaft[6 in anti-friction bearings I1, and in a second bearing 18 carried by amovable end plate l9 suitably attached to the gear casing I 0. Betweenthe. bearings l! and [8 a worm gear 20 is splined on the shaft is andengages the worm M. In this manner, the electric motor l5 may operatethe shaft 55 at a reduced speed. On the right-hand end 2!, viewed inFig. 2, a lifting drum is attached by a key 23. This drum comprises aninner cylindrical section 24 of a comparatively large diameter, an outercylindrical section 25 of a comparatively small diameter and atransitional more or less conical section 26 connecting the two sections24 and 25. A single peripheral groove 23 shaped to accommodate a liftingrope fl is provided on the outside of the drum 22 extending over thethree sections 24, 26 and 25. On the conical section 26 the groove 23may extend in a spiral fashion through V to 2 convolutions or may extendmore or less straight tangentially to the drum section 25. While theouter end of the rope extends downwardly, as shown at 21, carrying ahook or the like for attachment of the load, the other end of the ropeis firmly fixed to the drum.

To the left-hand end of shaft [6 there is detachably connected forcommon rotation therewith a sleeve 29. For the purpose of suchattachment the sleeve may have a transverse pin 30 engaging a diametralslot provided in the end face of the shaft it. A spherical head 34 of astud 32 extending into the sleeve 29 is axially attached to a cap 33which is suitably fixed to the end plate H! of the casing. A spiral leafspring 35 surrounds the sleeve 29 inside the cap 33 and has its innerend fixed to the sleeve 29 and its outer end fixed to the cap 33 whichthus constitutes a spring barrel which may be filled with oil to reducethe friction of the convolutions of the spring upon each other. The cap33 is held against rotary displacement on the end plate H) by suitablemeans not shown permitting to attach the cap in different angularpositions, whereby the cap may be detached, turned and re-attached againfor the purpose of adjusting the bias of the spring. The drum issurrounded by a suitable sheet metal casing 35 attached to the gearcasing H) by bolts 36 and its lower left quadrant, viewed in Fig. 1, iscut. out for the purpose of permitting passage of the rope 2'; to andfrom the drum. It will appear from Fig. 2 that the cross-section of thegroove 28 is so tapered as to exert a clamping effect. on the rope 21,so that its depth is about two to three times the diameter of the rope.

A switch provided inside of a switch casing- 3'! mountedon the bottom ofthe casing of motor i is so operable as to stop the motor when the ropehas either been fully unwound or fully wound up. For this purpose a bentarm 38 (Fig. 1) is suitably journalled for rotation about a verticalaxis, the lower end of such arm 38 forming a loop 39 embracing thedownwardly extending section of the rope 27. The loop 39 is sodimensioned as to be engaged by the rope 21 when the same approacheseither the left or the right end of the groove. The arm 38 is connectedby suitable links 40 to the switch provided in casing 31. Preferably,the motor i5 is a type and of a size permitting the motor to be suppliedwith energy from the electrical light installation. The spiral spring 34is so wound as to increase its bias by a rotation of the drum in adirection lowering the rope 21.

The embodiment illustrated in Figs. 3 and 4 is similar and differs fromthat shown in Fig. 1 primarily by the absence of the spiral spring 34.Similar elements of the hoist shown in Fig. 3 are designated byreference numerals obtained by adding 100 to the reference numerals usedin Figs. 1 and 2. Thus, the motor H5 is mounted on the gear casing H0 todrive the shaft H6 by means of a worm and a worm gear H6. The liftingdrum i221 has a peripheral groove which, as shown in Fig. 2, hasdifferent radii at axially spaced points. In this embodiment, however,there is provided an outer cylindrical section 150 in addition to thesections :24, $26 and 25.

When the motor is so operated by suitable actuations of the switch incasing 37 as to lower the load, the bias of the spring 34 is increased.Hence, when the load will be lifted, the spring will assist the electricmotor operated in the opposite direction of rotation and thus render itpossible for an electric motor with a limited power to lift a muchhigher load than it could do in the absence of the spring, provided themotor is reversible. In this manner, the present invention makes itpossible to equip a hoist of a given load lifting capacity with anelectric motor of but half the normal size, thus reducing both the costof manufacture of the hoist and its power consumption which is extremelyimportant in workshops where a great number of hoists are installed.Where A. C. motors are chosen and are to be installed in a workshopprovided with a three-phase main line, it is recommended, in order toobtain a uniform load on the main, to split up the hoists in threegroups connected between the three phases,

As a result of the difference in the diameter of the drum section 24, 25or I24, I25, 50 respectively, the load will be operated at differentspeeds when passing through different zones of elevation. That isillustrated in Fig. 4 with reference to the hoist shown in Fig. 3, thelifting speed of the load being shown as a function of the elevation ofthe load. Thus, it will be noted that the lifting speed amounts to 0.185meter per second when the load is lifted between A and B from the floorup to an elevation of 0.4 meter and that then the lifting speed drops to0.08 meterv from .B to C, while the rope l2? enters the spiral sectionof the groove provided on the conical intermediate section l28 of thelifting drum I22. While the load is lifted from a level 1.1 meters abovethe floor up to 1.75 meters, the lifting speed is kept constant at 008meter per second. Then the lifting speed is slightly increased between Dand E, while the rope ascends the section 150 of the drum. Between thelevel 1.85 meters and 2.2

meters above the floor the lifting speed amounts to 0.115 meter persecond.

The present invention is primarily applicable to cases where a reducedlifting speed, the socalled fine adjustment speed, is required within acertain range of elevations only. That applies for instance to hoistsused to carry a work-piece that is to be mounted on a tool-machine, forinstance on the spindle of a lathe. In that case the fine adjustmentspeed is needed at an elevation of from 1 to 1 meters. When therequirements of any particular case are known, the drum may be easily sodesigned as to meet such requirements. Another case to which the presentinvention is applicable with great advantage is the lifting of holdersout of a vat containing a chemical or a dye or the like. In that case asmall lifting speed of the holder is required within a certain rangeonly.

While I have described my invention with reference to two preferredembodiments thereof, I Wish it to be clearly understood that the same isnot limited to the details thereof but is capable of numerousmodifications within the scope of the appended claims.

What I claim is:

1. A hoist of the character described comprising a supporting structure,a horizontal bearing carried thereby, a shaft mounted in said bearing, aworm gear splined to such shaft adjacent to said bearing, a wormjournalled in said supporting structure and engaging said worm gear, anelectric motor mounted on said supporting structure in a drivingconnection with said worm. a lifting drum mounted on one end of saidshaft, a spiral spring mounted on the other end of said shat t, and 9,spring barrel surrounding said spring and attached to said supportingstructure.

2. A hoist of the character described comprising an overhead supportingstructure, a pair of spaced co-a-xial horizontal bearings carriedthereby, a shaft mounted in said bearings, a worm gear splined to saidshaft between said bearings, a substantially horizontal worm journalledin said supporting structure and engaging said worm gear at the topthereof, a reversible electric motor mounted on said supportingstructure co-axially and in driving connection with said worm, a liftingdrum mounted on one end of said shaft, said lifting drum having adjacentcylindrical sections of different diameters and a transitional conicalsection therebetween and a single peripherai groove extending over saidcylindrical sections and said transitional conical section foraccommodating a lifting rope, a spiral spring mounted on the other endof said shaft, and a spring barrel surrounding said springand adapted tobe attached to said supporting structure in different angular positions.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 152,145 McGlashan June 16, 1874 479,136 Ethridge July 19, 18921,015,459" Riggle Jan. 23, 1912 1,464,294 Reese Aug. 7, 1923 1,522,047Cragun Jan. 6, 1925 1,529,796 Kalbach Mar. 17, 1925 1,926,452 NorlingSept. 12, 1933 1,928,532. Gillespie Sept. 26, 1933 2,323,404 Kuchar July6, 1943 2,342,020 Stevens Feb. 15, 1944 2,481,037 Pringle Sept. 6, 1949

